TAILWINDS

Blinded by the light: Pilot night vision and the illusions of night flight

By:
The CTS Team •
September 4, 2017

How’s your night vision, and how can you improve it?

IFR or VFR, your ability to maximize your vision at night is important. Even if you aren’t flying by what you see outside your window, you still need to be able to read charts and instruments well in dim lighting, and you may need to perform visual approaches or spot an aircraft you need to avoid. Awareness of the limitations of human night vision can help improve your use of it, avoid dangerous illusions, and support better health and sleep cycles at the end of each flight.

The best-known limitation of night vision is the “central blind spot.” In a mostly dark area with low illumination on the periphery, a “blind spot” about 5-10” will appear at the center of your vision. This means that viewing distant or faint objects directly at night will result in them being invisible or even fading the longer you look at them.

The solution? A regular scan and liberal use of peripheral vision. Your peripheral vision is stronger than your central vision at night--the exact opposite of your vision during the day. You’ll need to use peripheral vision to keep dim objects in view, and make note of objects as you see them so you remain aware of them if they seem to disappear. Be aware, too, that it takes about 30-45 minutes in dim light to maximize your night vision, so use special care at the beginning of flight and keep cockpit lighting low and consistent.

You may also experience certain visual illusions when flying at night. As with other spatial disorientation factors, anticipating these illusions and understanding their true nature can help you identify and see through them. Some examples include:

Distant city lights or reflections over water may look like or blend into the stars, or vice versa, giving you the impression that the aircraft nose is higher or lower than actual.

A black hole illusion can occur on approach to a lit runway with no other lights in the surrounding area, giving the impression of a “black hole” between the aircraft and the runway itself. This can result in an unsafe or overestimated glide path.

By focusing on a fixed point of light in the distance, such as a star or a ground light, a pilot may experience the illusion that another aircraft is moving toward or in front of the aircraft.

In all of these cases, awareness that illusions may happen and trusting your instruments will help mitigate the associated risks.

Finally, be aware that night flight and the various levels of darkness and bright, electronic light that accompany it can have an affect on your physical health. Experts state that viewing screens (such as those of an EFB) late at night can make it more difficult to fall asleep and get a good night’s rest. Consider discussing the benefits of apps for your EFB that reduce blue light at night, and be sure to avoid screen time on the way home after a night flight or right before bed.